Not every US president gets a free private jet, but the Gulf states have boosted US economic dominance for decades

After signing a US$142 billion (£107 billion) arms deal with Saudi Arabia, Donald Trump said the US bond with that country was “more powerful than ever”. He was also reportedly quite pleased with the gift of a private jet from Qatar.

But these arrangements are just the latest developments in a long history of the Gulf monarchies supporting the architecture of American global power. And while the six Gulf states (Saudi Arabia, United Arab Emirates, Kuwait, Qatar, Bahrain and Oman) have...